SQL LEFT JOIN:

The LEFT JOIN keyword returns all rows from the left table (table1), even if there are no matches in the right table (table2).

Note that : the  left and  Right  joins  are  refered  as  OUTER  JOIN.

Syntax

SELECT column_name(s) FROM tablename1 as t1 LEFT JOIN tablename2 as t2 ON t1.column_name=t2.column_name

SQL LEFT JOIN Example:

The table “Customer” is,

Id	Name	Address	City
1	Vaishnavi	10,Anna Nagar	Bangalore
2	Shajil	23,T.Nagar	Chennai
3	Vinoth	20,Sivaji Street	Chennai

The  table “Order” is,

O_Id	OrderNo	Id
1	77895	3
2	44678	3
3	22456	1
4	24562	1
5	34764	15

Query:

SELECT C.Name, C.City, O.OrderNo FROM Customer as C LEFT JOIN Orders as O ON C.Id=O.Id

The result-set will be:

Name	City	OrderNo
Vaishnavi	Bangalore	22456
Vaishnavi	Bangalore	24562
Vinoth	Chennai	77895
Vinoth	Chennai	44678
Shajil	Chennai

The LEFT JOIN keyword returns all the rows from the left table (Customers), even if there are no matches in the right table (Orders).